MURDERERS and thieves beware. Human DNA has been identified in household dust for the first time.
The amount of DNA in dust is tiny and from so many people that singling out any individual could be tricky. With further research it might be possible to find ways of recreating someone鈥檚 profile or even working out how recently they鈥檇 visited a crime scene from the decay of their DNA.
The discovery that human DNA is detectable and measurable in dust is a first, say researchers who report their findings in Forensic Science International (). 鈥淧eople have quantified the amount of DNA in dust many times before, but no one had looked before for human DNA,鈥� says Bonnie Brown, co-leader of the team at Virginia Commonwealth University in Richmond.
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The team collected dust samples from various rooms around their campus, from highly trafficked classrooms to quieter offices. Most of the DNA they recovered came from bacteria or fungi, but there was human DNA in all but one of their 36 samples. Though each sample contained just trillionths of a gram of DNA, it was enough for amplification and profiling via the DNA kits used in forensic labs. But the read-outs contained overlapping signals from so many people that it was virtually impossible to pick out any one person鈥檚 DNA profile.
鈥淭here was human DNA in all but one of their 36 samples. Though just trillionths of a gram it was enough for profiling in a lab鈥�
Adrian Linacre of the Centre for Forensic Science at the University of Strathclyde in the UK says that as things stand, such evidence is of little forensic value. 鈥淔orensic investigators are already aware of background levels of DNA at crime scenes, and know when they鈥檙e not relevant to a case,鈥� he says.
The key is to connect DNA from a blood spot or hair to an event that took place. Most dust would have been left there by occupants of the room well before any event took place, Linacre says.
Brown hopes that the forensic usefulness of dust will improve with more research to uncover how fast DNA accumulates and how soon it degrades.
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